LTs+cats versus high flow cats only

[Fraxum]

I have searched and read many threads on LTs and high flow cats. I am talking about just these mods versus each other with no tune. I found this:

• LTs + high flow cats = 25 RWHP
• High flow cats with stock manifolds = 20-22 RWHP

So LTs are worth 3-5 HP? Of course we are not comparing the same cats. And then I see if you add a tune to either you see around another 6-8 RWHP.

Do I have this wrong? Are we adding LTs mostly for sound?

[The Stig]

The stock cats are very restrictive. Replacing them will free up a lot if rwhp. Yes getting high flow cats will give you some gains, but not the same.

[Fraxum]

Originally Posted by stieger

The stock cats are very restrictive. Replacing them will free up a lot if rwhp. Yes getting high flow cats will give you some gains, but not the same.

Yes I was wondering the amount of the difference.

BTW you have one of the best sigs here. It would be great to see the rest of that scene!

[Snake Slayer]

Originally Posted by Fraxum

I have searched and read many threads on LTs and high flow cats. I am talking about just these mods versus each other with no tune. I found this:

• LTs + high flow cats = 25 RWHP
• High flow cats with stock manifolds = 20-22 RWHP

So LTs are worth 3-5 HP? Of course we are not comparing the same cats. And then I see if you add a tune to either you see around another 6-8 RWHP.

Do I have this wrong? Are we adding LTs mostly for sound?

Yes and no LT plus Cat will net 25-30 RWHP untuned. A tuned setup can produce as much as 50rwhp.

[The Stig]

Originally Posted by Fraxum

Yes I was wondering the amount of the difference.

BTW you have one of the best sigs here. It would be great to see the rest of that scene!

Thanks, unfortunately I don't have the rest of the pic

[Fraxum]

Originally Posted by Snake Slayer

Yes and no LT plus Cat will net 25-30 RWHP untuned. A tuned setup can produce as much as 50rwhp.

I could be wrong But I have not seen a tune pick up 20-25 HP on just LTs+Cats no CAI, no ported TB.

My point is here that the big gain is from the cats. With your example the LT+Cats advantage over just high flow cats is between 5-8 RWHP. (20-22 versus 25-30). I assume the tune would pick up some HP on just high flow cats too.

I am questioning if LTs are all that on a bolt on car. I know a cam, stroker, or FI car will benefit. Wondering if it is worth the $$ when just doing boltons. Say you buy the Kooks for $800 you paid $100 per hp.

[Bad70supreme]

If your not going to run cats, just run OBX long tubes...thats a 30rwhp bolt-on for $350! I know some people flame them but for a guy like me not made of cash, thats a hard deal to beat! Those headers my not be the best quality, but they are just headers its not a moving part like a rocker arm! Those headers and a Ls9 cam is 50hp at the wheels for 550$ and your labor, thats my plan

[Fraxum]

Originally Posted by Bad70supreme

If your not going to run cats, just run OBX long tubes...thats a 30rwhp bolt-on for $350! I know some people flame them but for a guy like me not made of cash, thats a hard deal to beat! Those headers my not be the best quality, but they are just headers its not a moving part like a rocker arm! Those headers and a Ls9 cam is 50hp at the wheels for 550$ and your labor, thats my plan

I like the OBX, no bashing here. If I go LTs a low priced one will be my choice.

But my thoughts here are the LTS are not as responsible for most of the gain. The high flow cats are.

[JANNETTYRACING]

Originally Posted by Fraxum

I have searched and read many threads on LTs and high flow cats. I am talking about just these mods versus each other with no tune. I found this:

• LTs + high flow cats = 25 RWHP
• High flow cats with stock manifolds = 20-22 RWHP

So LTs are worth 3-5 HP? Of course we are not comparing the same cats. And then I see if you add a tune to either you see around another 6-8 RWHP.

Do I have this wrong? Are we adding LTs mostly for sound?

I don't believe for a minute that you will gain 20-22 RWHP buy just replacing your cats, More Like 12-15

A long Time ago in C5 world ADM made Cat Delete Pipes and found a gain of 18 at peak only.

Now We should not compare HP only at 6200 RPM

Long tube headers w high flow cats Consistantly pick up 25-28 RWHP at Peak but Gain upwards of 30 lb torque in the low and mid range over stock manifolds, THIS IS WHAT YOU FEEL on a daily driver.

Cats alone will not gain the torque that Long Tube Headers Gain.

See my Header Test results for Graphs.

Ted.

[Mark Myles]

Thank you for clearing this up Ted.

M

[Fraxum]

Originally Posted by JANNETTYRACING

I don't believe for a minute that you will gain 20-22 RWHP buy just replacing your cats, More Like 12-15

A long Time ago in C5 world ADM made Cat Delete Pipes and found a gain of 18 at peak only.

Now We should not compare HP only at 6200 RPM

Long tube headers w high flow cats Consistantly pick up 25-28 RWHP at Peak but Gain upwards of 30 lb torque in the low and mid range over stock manifolds, THIS IS WHAT YOU FEEL on a daily driver.

Cats alone will not gain the torque that Long Tube Headers Gain.

See my Header Test results for Graphs.

Ted.

I guess I was believing the Solo initial test @ 22 rwhp. I have not seen an independent before and after of just Solo cats. So you are saying the LTs are worth 7-10 RWHP and some extra torque.

What would be interesting would be these tests on the same stock car and same dyno:

• Stock
• High flow cats
• Shorties + high flow cats
• LTs+High flow cats

And each of the last three with a tune. I am just saying.

[Bad70supreme]

High flow cats are not cheap, and yes they do add a nice power gain... but LTs out perform them in every way. I personally dont think they are worth the money unless you have to use them. Once you start to really mod the high flow cats wont cut it anymore and you will end up putting LTs on it anyway

[mikeSS]

Originally Posted by Bad70supreme

High flow cats are not cheap, and yes they do add a nice power gain... but LTs out perform them in every way. I personally dont think they are worth the money unless you have to use them. Once you start to really mod the high flow cats wont cut it anymore and you will end up putting LTs on it anyway

that is so true. one of the main reason why i got rid of my high flow cats is because i wanted to add a cam and also wanted more sound. high flow cats are great for what they do. but if you are going to tune you better get LTs